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Discussion Starter · #1 ·
My HVAC system has been acting up for a while now and I can't find any threads that talk about the specific problem I am having. Most of the time when I start up my 2007 Solstice GXP, there will be a clicking noise (not the fuel pump clicking) (about 2 clicks per second, almost like the turn signal but slightly different) coming from right behind the gauge cluster. If it is clicking, the HVAC system will only blow out hot air no matter if AC is on or not or if temperature dial is all the way to cold (also know about the 1 click heating issue). If it is not clicking (rarely happens), then the AC will work, but usually only when temp dial is all the way to cold. In the past I have been able to do the recalibration and that would make it work for a while, however when I tried that this weekend, a loud thumping noise started from the middle of the dash and the recalibration never completed. This put the HVAC system into emergency mode. Anyone have any suggestions? I haven't tried soldering the resistor in place because it seems like there is something larger going on than just that. Any help would be appreciated.
 

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I suspect that your temperature mode door actuator interface is stripped. The clicking you're hearing is likely the actuator attempting to move the door and find the "limits" of the door travel. When the motor can't find the limits because the gear is stripped (or other problem), the system defaults to Defrost.

1) It appears that you're able to change where the air exits (dash, defroster & floor). is this correct?
2) The noise is the same regardless of the fan/blower speed.
3) After the engine is warm try slowly changing the temperature from cold to hot and back while the air is directed out the dash vents. Take about 10 seconds to turn the dial in each direction and note if there are any change in the noise. Start this at the low blower speed (Zero) and repeat at the other speeds. Does the temperature change?
4) Take note if you hear a "Foop - Clunk" noise during the process. This would be the air pushing the door from position to position.

I'll need to refresh my knowledge of the system, but this should be a good starting point.
 

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jrf is spot on from my understanding of the hvac system (though I'm no expert.) That certainly sounds like what's going on.
 

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More HVAC diagnosis

The temperature is controlled by two doors, a “left” and a “right” side. These doors are controlled by electric actuators that are on the left (driver’s side) of the HVAC module and work in unison to adjust the temperature. The actuators are the same (p/n 10397365) and are accessed by removing the driver’s side closeout under the dash. They are black square-ish (3” x 3” or so) devices that should be visible just above the trans tunnel. You’ll see three of them, you’re interested in the bottom two. Do a general inspection, although I’m not sure a problem would be obvious. The end of the actuator rotating shaft should be visible. With the ignition on, change the temperature setting and look for movement on the shaft end. In your case they both should move and hopefully one will exhibit the clicking you describe but it may be difficult to discern which. You can touch them as they move and you may be able to feel the “clicking.”

If you’re handy enough, you can remove the actuator(s) and inspect the interface between the temperature mode door and the actuator and observe if there’s anything that looks broken, warped, displaced, etc. You may also be able to rotate the door shaft to determine if it moves freely.

Hopefully you will find that the actuator is stripped-out or otherwise damaged and can be replaced and that the door moves freely. If the problem is with the door, the repair may be significantly more involved (i.e. remove the entire dashboard).

What is found in a general inspection will determine the next steps.

Edit: There are gears internal to the actuator that may also be stripped. There may not be any observable problem if this is the case.
 

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Discussion Starter · #5 ·
JRF,

Thank you for all the help. I did some investigating last night on my drive home after your first post. The information is below. I haven't had a chance to look into the information from the second post yet. I might not get to that until this weekend.

1) It appears that you're able to change where the air exits (dash, defroster & floor). is this correct? No, I am not able to change the location. It only blows out the dash.
2) The noise is the same regardless of the fan/blower speed. Correct, the volume and pulse do not change with blower speed or vehicle speed.
3) After the engine is warm try slowly changing the temperature from cold to hot and back while the air is directed out the dash vents. Take about 10 seconds to turn the dial in each direction and note if there are any change in the noise. Start this at the low blower speed (Zero) and repeat at the other speeds. Does the temperature change? Temperature did not change. It was incredibly warm the entire time.
4) Take note if you hear a "Foop - Clunk" noise during the process. This would be the air pushing the door from position to position. Did not hear any new noise during the process. The air flow rate did depend on vehicle speed, even with control knob set at 0.
 

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Hmmm. Considering that you're having issues with the mode as well, it's unlikely my original thought.

At a vehicle standstill, does the blower fan change as you change the speed setting? Your last comment makes me think it doesn't.

Which would indicate that pretty much nothing works as it should. This would point me in the direction of a HVAC control unit (the knobs) or a 12V power interruption somewhere within the system. I'll need to look into it a little deeper now.
 

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Discussion Starter · #7 ·
I was able to look into it more yesterday and I think I was able to find the culprit. The first actuator was what was clicking. I was easily able to disconnect it and remove it, re-calibrate the HVAC system and it seems like everything is working well again. I'm guessing that the first actuator turns on and off the recirculation mode, but I'm not positive. I was able to get AC, change locations and fan speed. I'm going to order a new one today and install it next week. I didn't drive the car today, so I don't know for sure that it completely solved everything, but I should know more after this weekend.

JRF, the speed setting did change before, except that it would not go to 0 when driving. When at rest I was able to change the fan speed. I'm not sure if it will now go do 0 when I am driving. I appreciate the help so far.
 

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Actuator fix?

Glad to help! Sounds like my 1st guess was close.

Hopefully the actuator is the absolute root cause simply because it a relatively cheap and simple repair.

As for the Zero setting on the blower: This is essentially a "ram air" type setting. At speed, air will still be forced through the HVAC system even with the fan off. So that part of the system is working as I'd expect.

Good luck! Be sure to post on if the replacement actuator fixes the problem.
 
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